The present invention relates to a device for postoperative autotransfusion, particularly in heart surgery.
It is known that the technique of postoperative autotransfusion is used particularly in heart surgery and consists in collecting the blood spilled by the drainages of the surgical wound, evacuating it together with air from the pleural-mediastinal cavity of a patient in order to reinfuse it into the patient after filtration.
The classical method, which can be performed without problems in the first hours after the operation, when the patient is under assisted ventilation, requires the adoption of a system which comprises a chamber which is connected to a vacuum generator, typically provided as a water seal valve which ensures downstream, in a known manner, the constancy of the degree of vacuum, and the direct connection thereof to a blood collection chamber which is connected to the drainages of the patient and thus receives the blood by way of the suction determined by the vacuum that is present therein.
In an evolution of the system, a water seal has been introduced in an intermediate position with respect to the above-described suction control and blood collection chambers; such seal ensures the monitoring of the air arriving from the patient and acts as a reflux-preventing valve which prevents the entry of air at atmospheric pressure into the pleural cavity, so as to avoid collapse of the lungs.
In this configuration, the system is used without problems both when the patient is under assisted ventilation and when the ventilation ceases and the patient breathes autonomously, and is further such as to allow a variation in the operating protocol which is sometimes adopted for clinical reasons and consists in so-called gravity drainage, in which the system is disconnected from the vacuum generator and the blood mixed with air is made to reach the collection chamber by gravity.
In order to provide this variation, it is important to provide, within the water seal, a maximum negative pressure valve, adapted to prevent external events, such as coughing of the patient or squeezing of the tubes on the part of the operators, from bringing the blood collection chamber to excessive negative pressure values.
The system provided with the above-described three chambers, respectively for suction control, water sealing and blood collection, has considerable positive features, but in the currently known embodiment it has some drawbacks which consist of the presence of pumping means for transferring the blood from the collection chamber to a bag which is meant to be connected to the patient for reinfusion, or directly to the patient, and further has a certain operating complexity which the operator encounters in various steps of operation.
The aim of the present invention is therefore to provide a device for postoperative autotransfusion particularly in closed-circuit heart surgery which provides maximum simplicity of operation, with assurance of absolute safety against the possibility of errors, in any functional condition, and further allows to transfer the blood from the collection chamber to a normal bag to be connected to the patient without requiring the adoption of any pumping means.
Within this aim, an object of the invention is to provide a device in which the bidirectional passage of liquids between the water seal and the blood collection chamber is prevented and in which sterilization of the air that passes from one chamber to the other is ensured.
This aim and this and other objects which will become better apparent hereinafter are achieved by a device for postoperative autotransfusion particularly in heart surgery, according to the invention, which comprises, functionally connected in a monolithic unit: a suction control chamber, which is adapted to be connected to a vacuum generator by means of a tube; a blood collection chamber, which is provided at the bottom with a cock adapted to be connected to a bag and is adapted to be connected by means of at least one tube to the drainage system of a patient; and a water seal, which is interposed between said chambers and comprises two ducts which are interconnected at the lower end and are connected, at the upper end, respectively to the suction control chamber and to the blood collection chamber, a union being provided proximate to the end that is connected to said blood collection chamber, said union being connected to the atmosphere by means of a tube, characterized in that it comprises means which are adapted to act simultaneously on said tubes connected to the atmosphere and to the drainage system of a patient, so as to selectively provide a condition in which the tube connected to the atmosphere is closed and the tube connected to the patient drainage system is open, and a condition in which said tube connected to the atmosphere is open and said tube connected to the patient drainage system is closed.
In a device comprising the three chambers described above, respectively the suction control chamber, the water seal chamber and the blood collection chamber, advantageously there is, between the water seal and the blood collection chamber, a membrane which is hydrophobic and as such prevents the bidirectional flow of liquids and sterilizes the air that passes through it.